Ericsson R310 on this page is a Phone Batteries search, not a nearby aisle with a similar title. Read the spec line and the in-box list before you compare price. Two cards can share a phrase and still be different products.
Open two or three phone batteries cards, check the same printed field, then pick one you can use this week.
Write down the model or size you need for Ericsson R310. Availability and price still belong on the product page.